一次创建多个多态记录

Question

我有与此处描述的完全模式相同的多态连接表:http://aaronvb.com/articles/a-polymorphic-join-table.html

class Location < ActiveRecord::Base
  has_many :note_joins, as: :notable
  has_many :notes, through: :note_joins
end

class Checkpoint < ActiveRecord::Base
  has_many :note_joins, as: :notable
  has_many :notes, through: :note_joins
end

class NoteJoin < ActiveRecord::Base
  belongs_to :notable, polymorphic: true
  belongs_to :note
end

class Note < ActiveRecord::Base
  attr_accessible :content, :user_id
  belongs_to :notable, polymorphic: true
  belongs_to :user

  has_many :note_joins
end

我希望能够一次创建和更新多种类型的多态关联,而不必执行@note.locations << Location.first或更新@note.checkpoints << Checkpoint.first.

有点像@note.create note_joins_params并且@note.update note_joins_params会很棒的东西.

到目前为止,我能够实现创建部分的方法是将一系列属性传递给@note.note_joins.create,例如:

note_joins_params = [{"notable_id"=>"9225", "notable_type"=>"Location"}, {"notable_id"=>"9220", "notable_type"=>"Checkpoint"}]
@note.note_joins.create note_joins_params

是否有更多的Rails方式来实现这一点,或者适当的属性哈希语法类似于accepts_nested_attributes或类似的东西？

我知道如何做的唯一方法update是首先删除连接表中的所有现有记录,然后重新创建它们,即

@note.note_joins.destroy_all
new_note_joins_params = [{"notable_id"=>"9225", "notable_type"=>"Location"}, {"notable_id"=>"9220", "notable_type"=>"Checkpoint"}]
@note.note_joins.create new_note_joins_params

Answer 1

对于你想要完成的事情,如果你没有指定,那么Rails实际上没有接受嵌套属性的'smart_way' source_type.参考这个多态的另一面:通过关联

但你可以尝试这个:

class Location < ActiveRecord::Base
  has_many :note_joins, as: :notable
  has_many :notes, through: :note_joins

  accepts_nested_attributes_for :notes
end

class Checkpoint < ActiveRecord::Base
  has_many :note_joins, as: :notable
  has_many :notes, through: :note_joins

  accepts_nested_attributes_for :notes
end

class NoteJoin < ActiveRecord::Base
  belongs_to :notable, polymorphic: true
  belongs_to :note

  accepts_nested_attribute_for :note
end

class Note < ActiveRecord::Base
  attr_accessible :content, :user_id
  belongs_to :user

  has_many :note_joins
  # add these, otherwise you won't be able to do nested attributes
  # refer to the blog post I link above.
  has_many :locations, through: :note_joins, source: :notable, source_type: 'Location'
  has_many :checkpoints, through: :note_joins, source: :notable, source_type: 'Checkpoint'
end

然后在你的表单中,构建这样的东西:

# In your form

# if you want to create from the note, do this
<%= form_for @note do |f| %>
  <%= f.text_field :some_note_field %>
  <%= text_field_tag 'note[locations_attributes][][some_location_field]' %>
  <%= text_field_tag 'note[checkpoints_attributes][]some_checkpoint_field]' %>
<% end %>

# if you want to create from the location/checkpoint, do this.
<%= form_for @location do |f| %>
  <%= f.text_field :name %>
  <%= text_field_tag 'location[notes_attributes][][body]' %>
<% end %>


# In your Location/Checkpoint controllers

def create
  @location = Location.create(location_params)
  redirect_to @location
end

def location_params
  params.required(:location).permit(:name, notes_attributes: [:body])
end

# In your Note controller
def create
  @note = Note.create(note_params)
  redirect_to @note
end

def note_params
  # the goal here is to create a set of params like this
  # { note_field: 'foobar',
  #   locations_attributes: [{name: 'somewhere'}],
  #   checkpoints_attributes: [{description: 'lol'}] }
  params.required(:note).permit(:note_field, locations_attributes: [:location_field], checkpoints_attributes: [:checkpoint_field])
end